Unsubscribed but still charged for premium

[seokso]

I unsubscribed from the premium service weeks ago -or at least I thought I had. I went to the accounts page, clicked to unsubscribe, answered why, gave my password, and saw the goodbye message. Everything appeared to go through correctly and I haven't really used the service enough since then to notice if there were any ads or not. This was cancelled well before my trial period was up. Then today, I saw a bill on my credit card. I've gone through and unsubscribed for a second time so hopefully it will work this time, but is there any way to get the bill removed from my card? I don't want to pay for a service I just don't use.